Method of transmitting electric potentials



Sept. 19, 1933. w. ROGOWSKI ET AL 1,927,755

METHOD OF TRANSMITTING ELECTRIC POTENTIALS Filed April 9, 1931 Patented Sept. 19, 1933 METHOD OF TRANSMITTING ELE'oTRTo Pop TENTIALS Walter Rogowski, Walter Grosser, andiJohann 1 I t Peek, Aachen, Germany v Application April 9, 1931, Serial No. 52 ,934, and in Germany March 8, 1930 V I 2 Claims.

For many purposes, such as in amplifiers, it is necessary to transmit the potential difference arising between a pair of points of a circuit to another pair of points. h I I I The invention has for its object to provide a simple, and most efiicient method for efiecting such transmissions, the main feature residing in the use of glow discharge lamps which permit of transmitting not only quick but also slow potential variations.

In order to allow of the invention to be clearly.

understood we shall now proceed to describe it with reference to the accompanying drawing.

Fig. l is a diagram of a system according to the invention, Fig. 2 illustrates a characteristic of the relation between current and voltage of a glow discharge lamp, Fig. 3 is a diagram of an amplifier embodying the invention.

:The problem in question is to transmit the potential difference arising between any selected points a andb of a circuit to another pair of points 0 and d. The potential between the points a and I) often consists of a direct current voltage U1 superposed by a voltage AU1, for instance a pure alternating current voltage, which is dependent on the time. In these cases, the transmission of the total potential U1+AU1 to the terminals 0 and d should generally be so current voltage U2 difierent from U1 and an alternating current voltage AUz superposed on the voltage U2 and dependent on the time and proportional to the voltage AU1.

Potential transmissions have to be efiected, for instance, in amplifiers between the anode of one of the potential amplifying tubes to the grid of the next tube. The requirement in these cases is a transmission, true within vast limits, of the variations of the anode potential to the grid and a simultaneous transition from the amount of the positive direct current voltage of the anode td the generally negative biasing voltage of the grid.

Most of the methods of potential transmission known hitherto have the fundamental drawback that very slow potential variations are not transmitted at all or only very badly. The transmission by means of a transformer and the known resistance condenser coupling in a normal resistance amplifier belong to these known methods of transmission.

llhe known methods designed to transmit also slow potential variations have other drawbacks, 55 which are in part'of electrical nature, such as suppression of high frequencies, and in part of that it produces between these terminals a direct economical nature, suchzas. an increasedexpenditure of direct current sources- 1y; a. In contradistinction to the known arr, nee.- ments, there are used according ;to the invention one or more glow discharge'lampsby means of 6.9 which it is possible to transmit not only quickbut I also slow" potential variations. 15" A simple embodiment of .asystem'" according to the inventionis shown in Fig; 1.: Connected between a and c is a discharge 1amp-e",.betw,een. c and d 'a'direct current sourceg and a-high resistance h, preferablyv anohm resistance. ,The conditions are so chosen that the. discharge lamp burns constantly. v

l. -A glow discharge lamp essentiallydifiers: in IQ its behaviour from an ohm resistance in that the course of the relation between current. and voltage is not linear but in accordance withx a characteristic such'as illustratedinFig.:24, It is a particular property of the discharge lamp that the potential remains practically unchanged within a certain current range. If. there zis; in this range'a direct'currentan'dan'alternatin'g current superposed on .the former,xthe*-voltage at the lamp remains substantiallyconstant-that is to say the alternating current resistance of; the lamp is practically zero or at least very small. The direct current resistance R9 of the lamp is determined by the proportion of the direct current voltage to the respective direct Q35 current, it being very high. Normal values for the alternating current resistance and the direct current resistance are, for example, 10000 ohms and 2, 3 megohms; v

The resistance h of Fig. l is preferably chosen so that it is small with reference to the direct current resistance and large with reference to alternating current resistance of the discharge lamp. Thereby, it is attained that, on the one hand, almost the full value. of the potentia'l variations AU1. istransmitted to the points 0 v and d, and on the other hand an'auxiliary'bat I tery g of small voltage. suflices to obtain the desired direct current voltage Uz between c 100 and d. r r v If the direct current resistance of the discharge lamp is 2, 3 megohms, its alternating cur-' rent resistance 10000 ohms, and if the resistance rnating current voltage AU1.

variation AU1, the maximum value of which may under these conditions be about 5 volts with a discharge lamp of the characteristic illustrated in'Fig. 2. As the discharge lamp is practically entirely independent as to frequencies, the system according tovFigr 1 works practically independent as regards the quickness of the potential variations AUi.

Instead of only one discharge lamp, there'may also be used a plurality of lamps, connected in series or in parallel or in suitable combinations. If instead of the resistance h there is used an element which offers no essential resistance to direct current, it maybecome ,necessary to add still one'or more resistances (ohm resistances) for, stabilizing the discharge lamp current. Instead of the direct current sources there may also be used direct current potential drops at'ohm resistances. v

Fig. 3 shows the present invention'as applied to an amplifierflworking with thermionic valves.

The periodic or aperiodic potential to be amplithe controllgrid of a thermionic valve The zpotential variations occurring at the resistance '7: inserted in the anode circuit are transmitted through a glow discharge lamp 6 to a resist- The potential variations arising at Z control another thermionic valve m. 0 is a The source negative prepotential. v

'I'he showing in Fig. '1 is based on the assum- 'tion that the potential between a and b is composedof a battery voltage U1 and a pure alter- 7 However, the potential U1+A U1 between a and b may, indeed,

be produced anyhowand AU1 may anyhow be dependent on the time.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In an electric system for transmitting potential variations, in combination a pair of electric conductors having applied to theme. varying potential, another pair of conductors' to which the variations are to be transmitted, an electric resistance and a source of direct current voltage in series between the two last said conductors, an electric connectionbetween one conductor of the first and one conductor of the second pair of conductors, an electric connection between the remaining two of the fourconductors, at

keeping the gas discharge tube constantly burn ing during the operation of the system.

2. In an electric amplifying system, in combination at least two amplifying tubes, at source of direct current voltage and an electric resistance in series between the anode and thecathode of the first amplifying tube, a source of direct current voltage and an electric resistancebetween the, grid and the cathode of the second amplifying tube, an electric connection between the cathodes of the two amplifying tubes, an electric connection between the anode of the first and the grid of the second amplifying tube,

and at least one gas discharge tube in the last 7 said connection, this discharge tube having an operating voltage allowing it to constantly burn during the working of the system and adapted to transmit the potential variations of the anode of the first amplifying tube to the grid of the other amplifying tube.

WALTER ROGOWSKI.

WALTER GRCissER. JOHANN PEEK. 

